Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
I'm trying the Javier's CappingEffect example and it seems to work fine...but only when I look at the scene from one side...if I move the camera to the opposite side I still see the cappings that are drawn over my geometry (they should be hidden instead)...please refer to the attachments to see what I mean. In order to use the CappingEffect I modified osgviewer in this way: Code: osg::ClipNode* clipnode = new osg::ClipNode; osg::ClipPlane* clipplane = new osg::ClipPlane(); clipplane-setClipPlane(0, 1, 0, 1); clipnode-addClipPlane(clipplane); clipnode-addChild(loadedModel.get()); CappingEffect* capping_effect = new CappingEffect; capping_effect-addChild(clipnode); scene-addChild(capping_effect); viewer.setSceneData(scene); How can I solve the issue? Thanks. Alessandro -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=41807#41807 Attachments: http://forum.openscenegraph.org//files/capping_2_434.png http://forum.openscenegraph.org//files/capping_1_109.png ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Javier, Thanks so much for the link. I haven't seen this thread before. I'm looking at your code and I'm not exactly sure how the CappingEffect node fits into the scene graph. Say I want to cut the cow in half and cap it. I am going to need a ClipNode / ClipPlane and the CappingEffect node, correct? Do I then have to have a topmost group node, with CappingEffect and ClipNode children then have the cow scene be a child to both of those nodes? Cory On 7/26/2011 6:44 AM, Javier Taibo wrote: Hi Cory, Sorry I came a bit late to this thread, but just in case you sill find it useful, I sent some code to the list about a year ago, that implements the stencil technique described in the red book. It is in this message: http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2010-September/044664.html Regards, On Wed, Jul 20, 2011 at 5:48 PM, Cory Riddell c...@codeware.com wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] using ClipNode to cut a model in two, then cap the open side
Hi just an example of what can be done with ogs in this respect http://forum.openscenegraph.org/viewtopic.php?t=8512 ( also some hints ) Regards Sergey ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
ClipNode is positional state (like lights). It just needs to be somewhere in your scene graph, and it it in effect at *any* part of your scene graph that enables GL_CLIP_PLANEn. So the placement of ClipNode relative to the cow is irrelevant. Don't know about Javier's CappingEffect; I'd just use a Camera node to post-render a fullscreen quad with appropriate stencil settings. It'll only show up on the capped area if done correctly. Be sure to specify a normal that matches your clip plane for correct lighting. -Paul On 8/1/2011 2:15 PM, Cory Riddell wrote: Javier, Thanks so much for the link. I haven't seen this thread before. I'm looking at your code and I'm not exactly sure how the CappingEffect node fits into the scene graph. Say I want to cut the cow in half and cap it. I am going to need a ClipNode / ClipPlane and the CappingEffect node, correct? Do I then have to have a topmost group node, with CappingEffect and ClipNode children then have the cow scene be a child to both of those nodes? Cory On 7/26/2011 6:44 AM, Javier Taibo wrote: Hi Cory, Sorry I came a bit late to this thread, but just in case you sill find it useful, I sent some code to the list about a year ago, that implements the stencil technique described in the red book. It is in this message: http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2010-September/044664.html Regards, On Wed, Jul 20, 2011 at 5:48 PM, Cory Riddellc...@codeware.com wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- -Paul Martz Skew Matrix Software http://www.skew-matrix.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Hi Cory, Sorry I came a bit late to this thread, but just in case you sill find it useful, I sent some code to the list about a year ago, that implements the stencil technique described in the red book. It is in this message: http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2010-September/044664.html Regards, On Wed, Jul 20, 2011 at 5:48 PM, Cory Riddell c...@codeware.com wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- Javier Taibo ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] using ClipNode to cut a model in two, then cap the open side
I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Using stencil for capping is an old trick and works well. I don't know of any example code for it, and it's been years, more than a decade, since I've done it myself. Your only other option would be some type of CSG approach, which would be computationally expensive, especially if the clip plane is dynamic. -Paul On 7/20/2011 9:48 AM, Cory Riddell wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Paul, thanks for the opinion. I think I'm getting close to the limits of what I can do with OSG without knowing a thing about OpenGL (and I'm pretty stoked about how much I was able to accomplish without really knowing what I'm doing). Time to buckle down and learn some (modern) OpenGL. I'm going to start with Joe Groff's tutorial (http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html) and build from there. Thanks, Cory On 7/20/2011 12:00 PM, Paul Martz wrote: Using stencil for capping is an old trick and works well. I don't know of any example code for it, and it's been years, more than a decade, since I've done it myself. Your only other option would be some type of CSG approach, which would be computationally expensive, especially if the clip plane is dynamic. -Paul On 7/20/2011 9:48 AM, Cory Riddell wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Hi Cory, Have a look at the osgreflect example to see how you can set up stencil buffer usage in the OSG. Robert. On Wed, Jul 20, 2011 at 7:27 PM, Cory Riddell c...@codeware.com wrote: Paul, thanks for the opinion. I think I'm getting close to the limits of what I can do with OSG without knowing a thing about OpenGL (and I'm pretty stoked about how much I was able to accomplish without really knowing what I'm doing). Time to buckle down and learn some (modern) OpenGL. I'm going to start with Joe Groff's tutorial (http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html) and build from there. Thanks, Cory On 7/20/2011 12:00 PM, Paul Martz wrote: Using stencil for capping is an old trick and works well. I don't know of any example code for it, and it's been years, more than a decade, since I've done it myself. Your only other option would be some type of CSG approach, which would be computationally expensive, especially if the clip plane is dynamic. -Paul On 7/20/2011 9:48 AM, Cory Riddell wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
Hi Robert, The osgreflect example is the one I was using as a guide along with the article I linked to in my first post. I didn't get it working, but I have an inkling of how it should work. I really need to step back though and learn some fundamentals first. Cory On 7/20/2011 3:14 PM, Robert Osfield wrote: Hi Cory, Have a look at the osgreflect example to see how you can set up stencil buffer usage in the OSG. Robert. On Wed, Jul 20, 2011 at 7:27 PM, Cory Riddell c...@codeware.com wrote: Paul, thanks for the opinion. I think I'm getting close to the limits of what I can do with OSG without knowing a thing about OpenGL (and I'm pretty stoked about how much I was able to accomplish without really knowing what I'm doing). Time to buckle down and learn some (modern) OpenGL. I'm going to start with Joe Groff's tutorial (http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html) and build from there. Thanks, Cory On 7/20/2011 12:00 PM, Paul Martz wrote: Using stencil for capping is an old trick and works well. I don't know of any example code for it, and it's been years, more than a decade, since I've done it myself. Your only other option would be some type of CSG approach, which would be computationally expensive, especially if the clip plane is dynamic. -Paul On 7/20/2011 9:48 AM, Cory Riddell wrote: I've been thinking about using a ClipNode to cut my model in two to expose the inside details like a cutaway drawing. Just sticking a ClipNode at the root of my model graph does remove half of it, but the model ends up looking hollow rather than solid. I want to cap the open side. For example, if a sphere is cut in two, I would cap the open side with a circle. A bit of searching for how to do this with OpenGL turned up this page (http://glbook.gamedev.net/moglgp/advclip.asp) that caps the open side using the stencil buffer. Does the technique outlined in the article look like a reasonable OSG-friendly approach? Any advice or pointers to other examples? Grepping the example code turns up a bunch of stencil code, but I'm still a little lost (OpenGL newbie). Thanks, Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
On 7/20/2011 12:27 PM, Cory Riddell wrote: Paul, thanks for the opinion. I think I'm getting close to the limits of what I can do with OSG without knowing a thing about OpenGL (and I'm pretty stoked about how much I was able to accomplish without really knowing what I'm doing). Time to buckle down and learn some (modern) OpenGL. I'm going to start with Joe Groff's tutorial (http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html) and build from there. :-) There are a lot of people that try to write OSG code without knowing what's going on under the hood. I strongly recommend the OpenGL red book: http://www.amazon.com/OpenGL-Programming-Guide-Official-Learning/dp/0321552628/ref=sr_1_1?s=booksie=UTF8qid=1311193922sr=1-1 Enjoy, -Paul ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
On 7/20/2011 3:34 PM, Paul Martz wrote: :-) There are a lot of people that try to write OSG code without knowing what's going on under the hood. I strongly recommend the OpenGL red book: http://www.amazon.com/OpenGL-Programming-Guide-Official-Learning/dp/0321552628/ref=sr_1_1?s=booksie=UTF8qid=1311193922sr=1-1 I think that speaks a great deal about what the quality of the OSG abstraction. With only the vaguest of notions of how this stuff is working, I've been able to put together some really neat stuff. I'm curious, why didn't you suggest your own book? Because it isn't for version 3+? Do you recommend the red book over the superbible? One of the superbible reviews on Amazon says that they teach their toolkit rather than the underlying API and that worries me a bit. The red book reviews are even worse! Cory ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
On 7/20/2011 2:42 PM, Cory Riddell wrote: I'm curious, why didn't you suggest your own book? Modesty? I'll recommend Paul's book for LEARNING. The Red Book is fine, for reference. But having a Toyota Service manual doesn't help you understand how to drive a Camry. Because it isn't for version 3+? So little OGL3 is being done right now that I don't feel this is a limitation. Do you recommend the red book over the superbible? One of the superbible reviews on Amazon says that they teach their toolkit rather than the underlying API and that worries me a bit. The red book reviews are even worse! I was a technical editor on the latest SuperBible and I think it's a good book. It does use some underlying library code to gloss over some fiddly bits and make it possible to actually write understandable demo programs without having to invent fire and blacksmithing on every page. They do explain WHAT the library does and how it does it, so I think it's reasonable. I would not call it a toolkit. they teach using the OpenGL API, but they use the library code to fill in the boring parts that they're NOT teaching. I'd consider it slightly above the GLUT library -- stuff you have to do, but aren't interested in seeing over and over once you know what it's doing under the hood. I think everyone should own the Red Book, period (and Orange book while you're at it). But I think Distilled and SuperBible are much better for learning. Cory -- Chris 'Xenon' Hanson, omo sanza lettere. xe...@alphapixel.com http://www.alphapixel.com/ Digital Imaging. OpenGL. Scene Graphs. GIS. GPS. Training. Consulting. Contracting. There is no Truth. There is only Perception. To Perceive is to Exist. - Xen ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
On 7/20/2011 2:42 PM, Cory Riddell wrote: I'm curious, why didn't you suggest your own book? _OpenGL Distilled_ was intended for people that already knew 3D graphics concepts and just wanted an introduction to the OpenGL API. I assumed the reader already knew what a stencil buffer was, for example. I had to do this to keep the book small and (relatively) affordable, and there were already plenty of books on those subjects. On the other hand, if you'd like a copy and you're in the US, email me offline and I'll send you a free one. Because it isn't for version 3+? Yeah, that too. _OpenGL Distilled_'s black cover was appropriate, as it was sort of a tombstone for the old fixed-function pipeline, probably the last OpenGL book to focus solely on non-shader based rendering. Do you recommend the red book over the superbible? One of the superbible reviews on Amazon says that they teach their toolkit rather than the underlying API and that worries me a bit. The red book reviews are even worse! Honestly I haven't looked at the current versions of either book, but (in my opinion, based on older versions of both books) the red book generally does a more complete job of covering basic 3D concepts (and algorithms such as stencil capping) than the SuperBible. (I mean no disrespect to the SuperBible; I think the red book is superior thanks to the ARB's input, and Addison Wesley's expertise in the 3D field.) But this is subjective and others will certainly disagree with me. If you can afford it, reading through both books will only reinforce your 3D dexterity. -- -Paul Martz Skew Matrix Software http://www.skew-matrix.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] using ClipNode to cut a model in two, then cap the open side
On 7/20/2011 3:16 PM, Chris 'Xenon' Hanson wrote: I think everyone should own the Red Book, period (and Orange book while you're at it). But I think Distilled and SuperBible are much better for learning. Can I hire you as my PR man? :-) -- -Paul Martz Skew Matrix Software http://www.skew-matrix.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
